一、概述
Zuul的主要功能是路由转发和过滤器。路由功能是微服务的一部分，比如/client-a/转发到到a服务，/client-b/转发到到b服务。zuul默认和Ribbon结合实现了负载均衡的功能。
二、准备
将服务注册与发现这篇博客中的Eureka-Client-A工程，复制一份，名字修改为Service-Zuul。
三、工程修改
Gradle依赖修改为
dependencies { compile('org.springframework.cloud:spring-cloud-starter-netflix-eureka-client') compile('org.springframework.cloud:spring-cloud-starter-zuul:1.4.4.RELEASE') compile('org.springframework.boot:spring-boot-starter-web') testCompile('org.springframework.boot:spring-boot-starter-test') }在启动类上添加@EnableZuulProxy注解，开启路由功能。
import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.cloud.netflix.eureka.EnableEurekaClient; import org.springframework.cloud.netflix.zuul.EnableZuulProxy; @SpringBootApplication @EnableEurekaClient @EnableZuulProxy public class EurekaZuulApplication { public static void main(String[] args) { SpringApplication.run(EurekaZuulApplication.class, args); } }修改application.properties配置文件，将/client-a/开头的请求路由到eureka-client-a服务器
spring.application.name=service-zuul server.port=10010 eureka.client.serviceUrl.defaultZone=http://localhost:10001/eureka/ zuul.routes.api-a.path: /client-a/** zuul.routes.api-a.serviceId: eureka-client-a
四、测试
启动之前的Eureka-Server、Eureka-Client-A和当前的Service-Zuul工程，访问http://127.0.0.1:10001/
发现都已经注册到了注册中心，访问http://127.0.0.1:10010/client-a/client，会发现路由到了Eureka-Client-A
五、服务过滤
Zuul不仅有路由的功能，还有服务过滤的功能，做一些拦截验证。
新建MyFilter类
import com.netflix.zuul.ZuulFilter; import com.netflix.zuul.context.RequestContext; import com.netflix.zuul.exception.ZuulException; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.stereotype.Component; import javax.servlet.http.HttpServletRequest; /** * Created by wzj on 2018/5/24. */ @Component public class MyFilter extends ZuulFilter { private static Logger log = LoggerFactory.getLogger(MyFilter.class); /** * to classify a filter by type. Standard types in Zuul are "pre" for pre-routing filtering, * "route" for routing to an origin, "post" for post-routing filters, "error" for error handling. * We also support a "static" type for static responses see StaticResponseFilter. * Any filterType made be created or added and run by calling FilterProcessor.runFilters(type) * * @return A String representing that type */ @Override public String filterType() { return "pre"; } /** * filterOrder() must also be defined for a filter. Filters may have the same filterOrder if precedence is not * important for a filter. filterOrders do not need to be sequential. * * @return the int order of a filter */ @Override public int filterOrder() { return 0; } /** * a "true" return from this method means that the run() method should be invoked * * @return true if the run() method should be invoked. false will not invoke the run() method */ @Override public boolean shouldFilter() { return true; } /** * if shouldFilter() is true, this method will be invoked. this method is the core method of a ZuulFilter * * @return Some arbitrary artifact may be returned. Current implementation ignores it. * @throws ZuulException if an error occurs during execution. */ @Override public Object run() throws ZuulException { RequestContext ctx = RequestContext.getCurrentContext(); HttpServletRequest request = ctx.getRequest(); log.info(String.format("%s >>> %s", request.getMethod(), request.getRequestURL().toString())); Object accessToken = request.getParameter("token"); if (accessToken == null) { log.warn("token is empty"); ctx.setSendZuulResponse(false); ctx.setResponseStatusCode(401); try { ctx.getResponse().getWriter().write("token is empty"); } catch (Exception e) { } return null; } log.info("ok"); return null; } }- pre：路由之前
- routing：路由之时
- post： 路由之后
- error：发送错误调用
- filterOrder：过滤的顺序
- shouldFilter：这里可以写逻辑判断，是否要过滤，本文true,永远过滤。
- run：过滤器的具体逻辑。可用很复杂，包括查sql，nosql去判断该请求到底有没有权限访问。
服务重启，再次访问http://127.0.0.1:10010/client-a/client，界面显示如下
再次输入http://127.0.0.1:10010/client-a/client?token=1001
